Definitions for backbencherˈbækˈbɛn tʃər, -ˌbɛn-
Random House Webster's College Dictionary
back•bench•erˈbækˈbɛn tʃər, -ˌbɛn-(n.)
a member of the British Parliament or a similar legislative body who is not a party leader.
Origin of backbencher:
a member of the House of Commons who is not a party leader
A Member of Parliament who does not have cabinet rank, and who therefore sits on one of the backbenches or in one of the back rows of the legislature.